Backflow prevention valve

ABSTRACT

A backflow prevention valve includes a cylindrical case member having a plurality of holes formed in an upper end at a periphery thereof, a valve member disposed in the case member to be movable in an axial direction thereof, an urging device disposed in the case member for urging the valve member upwardly, and a liquid inflow pipe extending outwardly from the case member. The valve member includes a sealing portion at an upper surface thereof for contacting a peripheral edge of an inflow opening to close the same, and a plurality of guiding arms provided on a peripheral edge of an upper surface of the valve member. The guiding arms are slidably disposed in the holes so that the valve member is supported and guided by the guiding arms passing through the holes.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Divisional Application of Ser. No. 10/419,143 filed on Apr.21, 2003.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

The present invention relates to a backflow prevention valve attached toa tip of a fuel supply pipe for supplying fuel to a fuel tank of anautomobile. The backflow prevention valve is usually closed to preventbackflow of the fuel, so that when the automobile turns over or fallsdown, the fuel does not leak from the supply pipe. When the fuel issupplied to the fuel tank, a fuel liquid pressure opens the backflowprevention valve for the fueling.

As shown in FIG. 7, a backflow prevention valve v is attached to a tipof a supply pipe p for supplying fuel into a fuel tank t of anautomobile in order to prevent the fuel from leaking through the supplypipe p when the automobile turns over or falls down.

As shown in FIGS. 8(A) and 8(B), a conventional backflow preventionvalve has been disclosed in Japanese Patent Publication (Tokkai) No.11-78549. As shown in FIGS. 8(A) and 8(B), the backflow prevention valveis formed of a cylindrical case member a and a covering member b forclosing a lower end of the case member. An inflow opening c is formed atan upper end of the case member, and a liquid inflow pipe d with asmaller diameter is connected to the inflow opening c. A valve member eis disposed inside the case member a to be movable for opening andclosing the inflow opening c from inside.

The valve member e is formed of a cylindrical body, and has four guidingarms f formed on an upper peripheral surface of the cylindrical body atlocations shifted by 90 degrees with each other. A conical projection gis projected at a center of a top surface of the valve member e forregulating the fuel flow, and a ring-shaped sealing portion h isprovided at a lower peripheral edge.

The valve member e is disposed inside the case member a in a state thateach guiding arm f is inserted in the liquid inflow pipe d, and is urgedupward (toward the liquid inflow pipe d) by a coil spring i. Fourguiding grooves j formed between a pair of projecting strips along anaxial direction are provided on an inner surface of the liquid inflowpipe d at locations shifted by 90 degrees with each other. Each guidingarm f is fitted to slide inside each guiding groove j. The valve membere is supported and guided by the guiding arms f sliding inside theguiding groove j.

The, backflow prevention valve is disposed in the fuel tank t, like thevalve v shown in FIG. 7, when the liquid inflow pipe d is attached to anend of the supply pipe p of the fuel tank t. As shown in FIG. 8(A), thesealing portion h of the valve member e usually contacts the peripheraledge of the inflow opening c of the case member a from inside by anurging force of the coil spring i. Accordingly, the valve member ecloses the inflow opening c, so that the fuel inside the fuel tank doesnot leak through the supply pipe p.

When the fuel is supplied, as shown in FIG. 8 (B), the valve member emoves downward (toward the covering member b) against the urging forceof the coil spring i by a pressure of the fuel supplied into the fueltank through the liquid inflow pipe d from the supply pipe. Therefore,the inflow opening c of the case member a opens, so that the fuel flowsinto the case member a through the inflow opening c from the liquidinflow pipe d. Then, the fuel is supplied into the fuel tank from anoutlet (not shown) provided on the peripheral wall of the case member a.

However, in the conventional backflow prevention valve, the valve membere does not move smoothly when the fuel is supplied.

In other words, in the conventional backflow prevention valve, theguiding grooves j for guiding the valve member e are provided inside theliquid inflow pipe d, and eight projecting strips forming the guidinggrooves j are projected on the inner surface of the liquid inflow piped. Consequently, when the fuel is supplied, the fuel flow causesturbulence inside the liquid inflow pipe d, so that the valve member edoes not move smoothly due to the turbulence when a large amount of fuelis supplied at a high speed. Also, due to the turbulence, the valvemember e can be twisted or tilted, resulting in an unstable movement ofthe valve member e for closing the valve after the fueling.

The present invention is proposed in order to solve the above problems,and an object of the present invention is to provide a highly reliablebackflow prevention valve. The backflow prevention valve is usuallyclosed to prevent the fuel backflow, and also can be opened and closedreliably and stably during and after the fueling.

Further objects and advantages of the invention will be apparent fromthe following description of the invention.

SUMMARY OF INVENTION

In order to achieve the above-mentioned objectives, the presentinvention provides a backflow prevention valve attached to an end of asupply pipe inside a fuel tank for supplying fuel to the fuel tank. Thebackflow prevention valve includes a cylindrical case member with aninflow opening at one end and an outlet at the other end or a peripheralsurface or both, and a sealing portion contacting a peripheral edge ofthe inflow opening from inside the case member for closing the inflowopening. The case member includes a valve member movable in an axialdirection; an urging device for urging the valve member toward theinflow opening; and a liquid inflow pipe connected to the inflow openingfrom outside the case member. Further, the liquid inflow pipe has asmooth inner surface without unevenness. The liquid inflow pipe isattached to the end of the supply pipe inside the fuel tank. A sealingportion of the valve member usually contacts the peripheral edge of theinflow opening from inside the case member due to an urging force of theurging device to close the inflow opening. When the fuel is supplied,the valve member of the backflow prevention valve moves against theurging force of the urging device due to a fuel pressure flowing intothe tank through the supply pipe, so that the inflow opening opens.

In other words, in the backflow prevention valve of the presentinvention, a supporting guide device is provided for supporting andguiding the valve member to be movable for opening and closingmovements. The supporting guide device is provided between an innerperipheral surface of the case member and an outer peripheral surface ofthe valve member. The supporting guide device may be formed of a guidearm provided in the valve member and inserted in a guide groove providedon the peripheral surface of the liquid inflow pipe. Therefore, theliquid inflow pipe has a smooth inner peripheral surface withoutunevenness.

With this configuration, even when the fuel is supplied through theliquid inflow pipe from the supply pipe in a large amount at a highspeed, the fuel flows smoothly inside the liquid inflow pipe withoutgenerating turbulence. Thus, the valve member can open and closesmoothly during and after the fueling, thereby ensuring the valve memberto open and close smoothly.

According to the backflow prevention valve of the present invention, thevalve is usually closed reliably, so that the fuel does not flowbackward. Further, during and after the fueling, the opening and closingmovement is performed reliably and stably.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded sectional perspective view showing a backflowprevention valve according to the first embodiment of the presentinvention;

FIGS. 2(A), 2(B) are partial sectional views showing the backflowprevention valve, wherein FIG. 2(A) shows a state that the valve isclosed, and FIG. 2(B) shows a state that the valve is open;

FIG. 3(A) is an exploded sectional perspective view showing a backflowprevention valve according to the second embodiment of the presentinvention, and FIG. 3(B) is a partial sectional view showing a valvemember of the backflow prevention valve;

FIGS. 4(A), 4(B) are sectional views showing the backflow preventionvalve of the second embodiment, wherein FIG. 4(A) shows a state that thevalve is closed, and FIG. 4(B) shows a state that the valve is open;

FIG. 5(A) is an exploded sectional perspective view showing a backflowprevention valve according to the third embodiment of the presentinvention, and FIG. 5(B) is a partial sectional view showing a valvemember of the backflow prevention valve;

FIGS. 6(A), 6(B) are sectional views showing the backflow preventionvalve of the third embodiment, wherein FIG. 6(A) shows a state that thevalve is closed, and FIG. 6(B) shows a state that the valve is open;

FIG. 7 is a schematic view showing a fuel tank of an automobile; and

FIGS. 8(A), 8(B) are sectional views showing a conventional backflowprevention valve, wherein FIG. 8 (A) shows a state that the valve isclosed, and FIG. 8(B) shows a state that the valve is open.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereunder, the present invention is explained more specifically withreference to the embodiments of the present invention.

FIGS. 1 and 2(A), 2(B) show a backflow prevention valve according to thefirst embodiment of the present invention. As shown in FIG. 1, thebackflow prevention valve includes a cylindrical case member 1; a valvemember 2 disposed inside the case main member 1 to be movable along anaxial direction; a coil spring (urging device) 4 for urging the valvemember 2; and a covering member 3 for closing a lower end of the casemember 1.

A ring-shape wall plate is provided at an upper end of the case member1, and a circular inflow opening 11 is provided at a center of the wallplate. A liquid inflow pipe 5 with a smaller diameter than that of thecase member 1 is integrally connected to the inflow opening 11 fromoutside. Four ribs 12 (only three are shown in FIG. 1) are projected onan inner peripheral surface of the case member 1 along the axialdirection at positions shifted by 90 degrees with each other.Furthermore, four engagement holes 13 (only two are shown in FIG. 1) areformed at a lower end of the peripheral wall with an even interval.

As shown in FIG. 1, the covering member 3 attached to the lower end ofthe case member 1 is formed of a cylindrical main member 31 with abottom and four arc-shaped flanges 32 protruded at a lower endperipheral edge of the cylindrical main member 31. Also, four fan-shapedoutlets 33 are formed on a bottom of the covering member with an eveninterval, and a cone-shaped spring retainer projection 34 is protrudedat a center of an inner bottom surface. The main member 31 is providedwith four ribs 35 protruded on the inner peripheral surface thereof, andalso provided with engagement projections 36 protruded on the outerperipheral surface thereof for engaging engagement holes 13 provided onthe case member 1.

As shown in FIG. 2, the main member 31 is inserted into the lower end ofthe case member 1 to engage the engagement projections 36 of thecovering member 3 with the engagement holes 13 of the case member 1,thereby fixing the covering member 3 to the lower end of the case member1.

As shown in FIG. 1, the valve member 2 is formed of a cylindrical mainmember 21, and a partition wall 22 is formed inside slightly above themiddle of the cylindrical main member 21. A sealing member fittingportion 23 having a cylindrical shape with a short length is integrallyprovided at a center of an upper surface of the partition wall 22. Fourengagement projections 24 are protruded on a peripheral surface of thesealing member fitting portion 23, and four notched window portions 25are formed on a lower peripheral wall of the main body below thepartition wall 22. Also, as shown in FIGS. 2(A), 2(B), a projection 26is protruded at a center of a lower surface of the partition wall 22 forfixing an upper end of the coil spring 4.

A sealing member 6 formed of an elastic material such as a rubber isfixed to an upper end of the valve member 2. As shown in FIG. 1, thesealing member 6 is formed of a circular main member 61. A conicalcommutating member 62 is integrally projected at a center of an uppersurface of the circular main member 61, and a cylindrical foot portion63 is integrally projected at a center of a lower surface of thecircular main member 61. The foot portion 63 is put on the sealingmember fitting portion 23 of the valve member 2, and engagementdepressions 64 formed at an inner surface of the foot portion 63 engagethe engagement projections 24 of the sealing member fitting portion 23,thereby fixing the sealing member 6 to the upper end of the valve member2. Moreover, a circular projection wall 65 is protruded on an uppersurface of the main member 61 to constitute a sealing portion(hereinafter referred to as the “sealing portion 65”).

As shown in FIG. 2, the valve member 2 is housed inside the case member1 to be movable along the axial direction in a state that the sealingmember 6 faces the inflow opening 11. Also, the valve member 2 is urgedtoward the inflow opening 11 by the coil spring (urging device) 4attached between the projection 26 and the spring fixing projection 34of the covering member 3.

The valve member 2 abuts against and is able to slide relative to edgesof the ribs 12, 35 provided on the inner surface of the case member 1and the covering member 3. The ribs 12, 35 support and guide the valvemember 2 to move in a steady position.

The backflow prevention valve is attached to the end of the supply pipep for supplying the fuel to the fuel tank t in an automobile byconnecting the liquid inflow pipe 5 in the same way of the valve v asshown in FIG. 7. As shown in FIG. 2(A), in a usual state, the sealingportion 65 of the sealing member 6 fixed to the valve member 2 contactsthe peripheral edge of the inflow opening 11 of the case member 1 frominside due to the urging force of the coil spring 4. Thus, the inflowopening 11 is closed, thereby preventing the fuel and other volatilevapor from leaking through the supply pipe p of the tank t.

Next, when the fuel is supplied, as shown in FIG. 2(B), the valve member2 moves against the urging force of the coil spring 4 due to the fuelpressure infused into the tank t (refer to FIG. 7) through the liquidinflow pipe 5 from the supply pipe p (refer to FIG. 7), and the inflowopening 11 opens. The fuel flows into the case member 1 from the liquidinflow pipe 5, and the fuel is infused into the fuel tank t from theoutlet 33 provided in the covering member 3 through between the valvemember 2 and the inner surface of the case member 1. After the fuelingis completed, the coil spring 4 moves the valve member 2 toward theinflow opening 11. Accordingly, the sealing portion 65 contacts theperipheral edge of the inflow opening 11 from inside, and the backflowprevention valve returns to the closed state again, as shown in FIG.2(A).

According to the backflow prevention valve of the present embodiment, asdescribed above, the ribs 12, 35 provided on the inner peripheralsurface of the case member 1 and the covering member 3 support and guidethe valve member 2 to open and close the inflow opening 11. Further, theinflow pipe 5 has the smooth inner surface without any unevenness.Therefore, even when the fuel is infused in a large amount at a highspeed through the liquid inflow pipe 5 from the supply pipe p (refer toFIG. 7), the fuel flows smoothly inside the liquid inflow pipe 5 withoutgenerating turbulence. The valve member 2 opens and closes the inflowopening 11 smoothly during and after the fueling, thereby preventingunstable opening and closing movements of the valve member 2 due to theturbulence.

Therefore, the backflow prevention valve of the present inventionusually closes the valve surely, and can reliably prevent the fuelbackflow. Also, during and after the fueling, the valve member does notbecome unstable due to the turbulence of the fuel supplied as does theconventional valve shown in FIG. 8, thereby achieving the reliable andstable opening and closing movements.

FIGS. 3(A)–(B) and 4(A)–(B) show a backflow prevention valve accordingto the second embodiment of the present invention. In this valve, inplace of the valve member 2 in the first embodiment, a valve member 7having guiding slots 71 on a peripheral surface thereof is provided.Other components are used in the same way as the first embodiment.

As shown in FIGS. 3(A) and 3(B), the valve member 7 of the valve isformed of a cylindrical main member 72 with a top wall. Four guidingslots 71 are formed on the peripheral surface of the cylindrical mainmember 72 along the axial direction thereof at positions shifted by 90degrees with each other. A ring-shaped sealing member 8 having a sealingportion 65 similar to the first embodiment is attached on an uppersurface of the main member by a cap member 9.

The cap member 9 is formed in a cylindrical shape, and has an upper wallformed in a conical rectifying member 62. The cap member 9 is fixed to ahole formed at a center of the upper wall of the valve member 7. Thesealing member 8 is fixed between the cap member 9 and the upper wall ofthe valve member 7.

The valve member 7 is disposed inside the case member 1 and is urged bythe coil spring 4, similar to the valve member 2 in the firstembodiment. In this case, as shown in FIGS. 4(A) and 4(B), the valvemember 7 is in a state that edges of the ribs 12, 35 provided on thecase member 1 and the covering member 3 are fitted and capable ofsliding inside the guiding slots 71 provided on the peripheral surfaceof the valve member 7, thereby supporting and guiding opening andclosing movements of the valve member 7 stably.

As other configurations and functional effects are the same as the firstembodiment, the same reference numerals denote the same parts, and theexplanation is omitted.

FIGS. 5(A)–5(B) and 6(A)–6(B) show a backflow prevention valve accordingto the third embodiment of the present invention. In this valve, a valvemember 10 including four guiding arms 20 is provided in place of thevalve member 2 in the first embodiment. The guiding arms 20 are insertedin holes 15 formed in shoulder portions of a case member 1 a. Moreover,the guiding arms 20 are inserted in four guiding slots 51 formed on theouter peripheral surface of the liquid inflow pipe 5. Otherconfigurations are substantially the same as those of the firstembodiment.

The case member 1 a is provided with an inclined portion on a peripheraledge of the upper wall thereof. The guiding arms 20 of the valve member10 are inserted into the holes 15 formed in the shoulder portionextending from the inclined portion to near the liquid inflow pipe 5 atpositions shifted by 90 degrees with each other. Four outlet windows(outlets) 14 are formed on the peripheral wall of the case member 1 a.Note that the rib 12 in the case member 1 of the first embodiment is notformed on the inner surface of the case member 1 a.

Also, four pairs of projections are protruded on the outer peripheralsurface of the liquid inflow pipe 5 connected to the inflow opening 11of the case member 1 a along the axial direction, so that four guidingslots 51 are formed between the projections at positions shifted by 90degrees with each other, thereby communicating with the holes 15.

As shown in FIGS. 5(A) and 5(B), the valve member 10 is formed of acylindrical main member 30 with an upper wall. Four guiding arms 20 areprovided at a peripheral edge of an upper surface of the main member 30at positions shifted by 90 degrees with each other. The cap member 9 andthe sealing member 8 are fixed to the top surface of the main member 30similar to the second embodiment.

As shown in FIGS. 6(A) and 6(B), the valve member 10 is housed to bemovable inside the case member 1 a in a state that each guiding arm 20is projected outside through each hole 15. Each four guiding arm 20projecting from the case member 1 a is inserted and capable of slidingin each guiding slot 51 formed on the outer peripheral surface of theliquid inflow pipe 5.

In the backflow prevention valve, as shown in FIGS. 6(A) and 6(B), theguiding arms 20 slide inside the guiding slots 51 to support and guidethe valve member 10, so that the opening and closing movements of thevalve member 10 can be carried out stably. Also, the inner peripheralsurface of the case member la is formed without unevenness for guidingthe valve member 10. Accordingly, the fuel flows into the tank moresmoothly as compared to the valves in the first and second embodiments.In addition, the guiding arms 20 are projected upward from the valvemember 10. Since the main member 30 of the valve member 10 does not needto provide a guiding function, the main member 30 of the valve member 10can be made small, thereby reducing the sizes of the case member 1 a andthe valve.

In the backflow prevention valve of the third embodiment, as shown inFIG. 6(B), during the fueling, the fuel supplied into the case member 1a flows into the fuel tank through the outlets 33 provided on thecovering member 3 a as well as through outlet windows 14 provided on theperipheral wall of the case member 1 a. The covering member 3 a is thesame as the covering member 3 in the first and second embodiments exceptthat the covering member 3 a does not include ribs on the innerperipheral surface. Since other configurations and functional effectsare the same as those of the first embodiment and second embodiments,the same reference numerals are used for the same parts, and theexplanation is omitted.

In the backflow prevention valve of the third embodiment, the guidingarms 20 are inserted and capable of sliding in the guiding slots 51through the holes 15 to support and guide the valve member 10.Alternatively, the holes 15 are formed in approximately the samesectional shape and size as the guiding arms 20, and the guiding armsslide inside the holes 15, thereby supporting and guiding the openingand closing movements of the valve member 10. In this case, the guidingslots 51 can be omitted. Further, it is possible to configure that theholes 15 and guiding slots 51 support and guide the opening and closingmovements of the valve member 10 without omitting the guiding slots 51.

As described above, in the backflow prevention valves in the first,second, and third embodiments according to the present invention, theinner peripheral surface of the liquid inflow pipe 5 has a smoothsurface without unevenness. As shown in the first and secondembodiments, the supporting guiding device is provided between the innerperipheral surface of the case member 1 and the outer peripheral surfaceof the valve members 2, 7 for supporting and guiding the valve members2, 7 to be movable for opening and closing the valves. As shown in thethird embodiment, the guiding arms 20 provided in the valve member 10are inserted into the guiding slots 51 provided on the outer peripheralsurface of the liquid inflow pipe 5 for supporting and guiding the valvemember 10 to be movable for opening and closing the valve.

With these configurations, even when the fuel is infused in a largeamount at a high speed through the liquid inflow pipe 5 from the supplypipe, the fuel flows smoothly inside the liquid inflow pipe 5 withoutgenerating the turbulence. The opening and closing movements of thevalve members 2, 7, 10 can be carried out smoothly during and after thefueling without being unstable due to the turbulence.

Therefore, the backflow prevention valve usually closes the valve surelyand can prevent the fuel backflow reliably. Also, during and after thefueling, the opening and closing movements can be carried out reliablyand stably.

Further, the present invention is not limited to the above-mentionedembodiments, and the shape and combination of each configuration memberscan be changed diversely within the limits of the present invention.

As described above, according to the backflow prevention valve of thepresent invention, even when the fuel is infused in a large amount at ahigh speed through the liquid inflow pipe, the fuel flows smoothlywithout generating the turbulence inside the liquid inflow pipe, whichhas the smooth inner surface without unevenness. The opening and closingmovements of the valve members during and after the fueling can becarried out smoothly, and there are no unstable opening and closingmovements of the valve members due to the turbulence, so that the highlyreliable opening and closing movements can be achieved.

The disclosure of Japanese Patent Application No. 2002-189099 filed onJun. 28, 2002 is incorporated in the application.

While the invention has been explained with reference to the specificembodiments of the invention, the explanation is illustrative and theinvention is limited only by the appended claims.

1. A backflow prevention valve attached to a fuel supply pipe forpreventing a backflow of fuel, comprising: a cylindrical case memberhaving a peripheral wall, an inflow opening formed at one end, an outletformed in at least one of the other end and the peripheral wall, and aplurality of holes formed in an upper end at a periphery thereof, avalve member disposed in the case member to be movable in an axialdirection thereof and having a sealing portion at an upper surfacethereof for contacting a peripheral edge of the inflow opening to closethe same, and a plurality of guiding arms provided on a peripheral edgeof an upper surface of the valve member, said guiding arms beingslidably disposed in the holes so that the valve member is supported andguided by the guiding arms passing through the holes, an urging devicedisposed in the case member for urging the valve member toward theinflow opening, and a liquid inflow pipe extending outwardly from thecase member around the inflow opening and having a smooth inner surfaceto allow the fuel to smoothly flow through the backflow preventionvalve.
 2. A backflow prevention valve according to claim 1, furthercomprising a plurality of guiding slots provided on an outer peripheralsurface of the liquid inflow pipe for receiving the guiding arms so thatthe valve member is supported and guided by the guiding arms passingthrough the holes and sliding in the guiding slots.
 3. A backflowprevention valve according to claim 2, wherein said case member has ashoulder portion at the upper end thereof, said holes being formed inthe shoulder portion.
 4. A backflow prevention valve according to claim1, wherein said sealing portion includes a circular main member having asize less than that of an upper portion of the cylindrical main member,and a circular projection wall protruded on an upper surface of the mainmember to constitute a sealing portion.
 5. A backflow prevention valveaccording to claim 4, wherein said circular main member further includesa conical member projecting outwardly from a center of the circular mainmember.
 6. A backflow prevention valve according to claim 4, whereinsaid cylindrical main member includes a partition wall, said sealingportion being attached above the partition.
 7. A backflow preventionvalve according to claim 1, further comprising a covering memberattached to a bottom of the case member, said urging device beingdisposed on the covering member.